Haha, so it's longer than in most languages in Brazilian Portuguese too? In El Salvador's capital at least we usually sing an extended version that comes from a Mexican movie from the 50s (I think, I really don't know the origins). Also, in the extension the rhythm is the same.

I have no bloody idea. How on earth one would fit fødselsdag (birthday) into a song is beyond me.

In the alternative version of Spanish it doesn't mention the word "birthday". Actually, the word birthday means something similar to "year fulfilment" but with a less formal tone of course. So the song literally translates to something like "[I hope] that you fulfil them happy".